Disseminated Mycobacterium marinum infection and bacteremia in a child with severe combined immunodeficiency

Case Report: Nontuberculous mycobacterial infections in children with complete DiGeorge anomaly

Children with complete DiGeorge anomaly (cDGA) have congenital athymia, resulting in severe T cell immunodeficiency and susceptibility to a broad range of infections. We report the clinical course, immunologic phenotypes, treatment, and outcomes of three cases of disseminated nontuberculous mycobacterial infections (NTM) in patients with cDGA who underwent cultured thymus tissue implantation (CTTI). Two patients were diagnosed with Mycobacterium avium complex (MAC) and one patient with Mycobacterium kansasii. All three patients required protracted therapy with multiple antimycobacterial agents. One patient, who was treated with steroids due to concern for immune reconstitution inflammatory syndrome (IRIS), died due to MAC infection. Two patients have completed therapy and are alive and well. T cell counts and cultured thymus tissue biopsies demonstrated good thymic function and thymopoiesis despite NTM infection. Based on our experience with these three patients, we recommend that providers strongly consider macrolide prophylaxis upon diagnosis of cDGA. We obtain mycobacterial blood cultures when cDGA patients have fevers without a localizing source. In cDGA patients with disseminated NTM, treatment should consist of at least two antimycobacterial medications and be provided in close consultation with an infectious diseases subspecialist. Therapy should be continued until T cell reconstitution is achieved.

Mycobacterium marinum Infection and Interferon-Gamma Release Assays Cross-Reactivity: A Case Report

Mycobacterium marinum (M. marinum) is a pathogen that causes skin and soft tissue infections in people who work with contaminated water, such as fish handlers. M. marinum infection is mostly limited to patients with compromised immune systems. As per current guidelines, susceptibility testing is not routinely recommended^, although sporadic cases have been reported with resistance to routinely prescribed anti-tuberculous drugs. We report a case of a 61-year-old male taking adalimumab with ulcerative skin and soft tissue infection with positive interferon-gamma release assays (IGRA) identified as M. marinum and the treatment challenges involved in this case.

Mycobacterial diseases in patients with inborn errors of immunity

Clinical disease caused by the agent of tuberculosis, Mycobacterium tuberculosis, and by less virulent mycobacteria, such as bacillus Calmette-Guérin (BCG) vaccines and environmental mycobacteria, can result from inborn errors of immunity (IEIs). IEIs underlie more than 450 conditions, each associated with an impairment of the development and/or function of hematopoietic and/or non-hematopoietic cells involved in host defense. Only a minority of IEIs confer predisposition to mycobacterial disease. The IEIs underlying susceptibility to bona fide tuberculosis are less well delineated than those responsible for susceptibility to less virulent mycobacteria. However, all these IEIs share a defining feature: the impairment of immunity mediated by interferon gamma (IFN-γ). More profound IFN-γ deficiency is associated with a greater vulnerability to weakly virulent mycobacteria, whereas more selective IFN-γ deficiency is associated with a more selective predisposition to mycobacterial disease. We review here recent progress in the study of IEIs underlying mycobacterial diseases.

A disseminated Mycobacterium marinum infection in a renal transplant HIV-infected patient successfully treated with a bedaquiline-containing antimycobacterial treatment: A case report

BACKGROUND

Disseminated Mycobacterium marinum infections occur rarely, in immunocompromised patients. Treatment with a prolonged multi-drug regimen exposes patients to drug-drug interactions and side effects.

CASE REPORT

We report a case of disseminated M. marinum infection in a 54-year-old renal transplant, HIV-infected woman. Manifestations of the infection were cutaneous and subcutaneous nodules, mediastinal lymph nodes and left pulmonary infiltrate. Empirical treatment for non-tuberculous mycobacteria was initiated with rifabutin, ethambutol and azithromycin. After identifying M. marinum in sputum, due to unfavourable clinical evolution and severe drug-related adverse events, treatment was changed to doxycycline and rifabutin. Digestive and haematologic side effects motivated a change in antimycobacterial treatment to a combination of moxifloxacin and bedaquiline. Tolerance was satisfactory, and the patient was cured after 12 months of treatment.

CONCLUSION

We report (to the authors' knowledge) the first case of disseminated M. marinum infection successfully treated with a bedaquiline-containing regimen. Bedaquiline could be an alternative to recommended antimicrobial regimens in cases of non-tuberculous mycobacterial disease, including M. marinum infection.

microRNAs in Mycobacterial Infection: Modulation of Host Immune Response and Apoptotic Pathways

Our current knowledge of mycobacterial infections in humans has progressively increased over the past few decades. The infection of Mycobacterium tuberculosis causes tuberculosis (TB) disease, which has reasoned for excessive morbidity and mortality worldwide, and has become a foremost issue of health problem globally. Mycobacterium leprae, another member of the family Mycobacteriaceae, is responsible for causing a chronic disease known as leprosy that mainly affects mucosa of the upper respiratory tract, skin, peripheral nerves, and eyes. Ample amount of existing data suggests that pathogenic mycobacteria have skilled in utilizing different mechanisms to escape or offset the host immune responses. They hijack the machinery of immune cells through the modulation of microRNAs (miRs), which regulate gene expression and immune responses of the host. Evidence shows that miRs have now gained considerable attention in the research, owing to their involvement in a broad range of inflammatory processes that are further implicated in the pathogenesis of several diseases. However, the knowledge of functions of miRs during mycobacterial infections remains limited. This review summarises recent findings of differential expression of miRs, which are used to good advantage by mycobacteria in offsetting host immune responses generated against them.

Heat-inactivated Mycobacterium bovis protects zebrafish against mycobacteriosis

Control of mycobacterial infection constitutes a priority for human and animal health worldwide. However, effective vaccines are needed for the control of human and animal tuberculosis (TB). Adult zebrafish have become a useful model for studying the pathophysiology of mycobacterial infection and for the development of novel interventions for TB control and prevention. Recently, parenteral and oral immunization with the heat-inactivated Mycobacterium bovis vaccine (M. bovis IV) protected wild boar against TB. The objectives of this study were to provide additional support for the role of M. bovis IV in TB control using the zebrafish model and to conduct the first trial with this vaccine for the control of fish mycobacteriosis. The results showed that M. bovis IV protected zebrafish against mycobacteriosis caused by low and high infection doses of Mycobacterium marinum and provided evidence suggesting that the protective mechanism elicited by M. bovis IV in zebrafish as in other species is based on the activation of the innate immune response through the C3 pathway, with a role for the regulatory protein Akr2 in this process. These results encourage the use of M. bovis IV for TB control in different species.

Control of mycobacteriosis in zebrafish (Danio rerio) mucosally vaccinated with heat-inactivated Mycobacterium bovis

BACKGROUND

Mycobacterial infections greatly affect human and animal health worldwide, and vaccines are effective, sustainable and economic interventions for the prevention and control of these infectious diseases. Recent results support the use of zebrafish as a model for studying the pathophysiology of mycobacterial infection and for the development of novel interventions for tuberculosis (TB) control. Recently, we showed that oral immunization with the heat-inactivated M. bovis vaccine (M. bovis IV) protect wild boar against TB, and suggested that this vaccine may controls mycobacterial infection in other species.

METHODS

In this study we evaluated the effect of M. bovis IV on the control of mycobacteriosis in zebrafish mucosally vaccinated by immersion and challenged intraperitoneally with Mycobacterium marinum.

RESULTS

The results showed that the M. bovis IV administered by immersion protected zebrafish against mycobacteriosis caused by M. marinum by reduction in mycobacterial infection, the number of mycobacteria per granuloma and the number of granulomas per fish. An IgM antibody response against M. bovis antigens was developed in vaccinated fish. Evidences suggested that the protective mechanism elicited by mucosal vaccination with M. bovis IV in zebrafish was based on the activation of the innate immune response through the C3 pathway.

CONCLUSIONS

These results support the use of the M. bovis IV administered by immersion for the control of mycobacteriosis in fish.

Mycobacterium marinum

Mycobacterium marinum is a well-known pathogenic mycobacterium for skin and soft tissue infections and is associated with fishes and water. Among nontuberculous mycobacteria (NTM), it is the leading cause of extrarespiratory human infections worldwide. In addition, there is a specific scientific interest in M. marinum because of its genetic relatedness to Mycobacterium tuberculosis and because experimental infection of M. marinum in fishes mimics tuberculosis pathogenesis. Microbiological characteristics include the fact that it grows in 7 to 14 days with photochromogenic colonies and is difficult to differentiate from Mycobacterium ulcerans and other mycolactone-producing NTM on a molecular basis. The diagnosis is highly suspected by the mode of infection, which is related to the hobby of fishkeeping, professional handling of marine shells, or swimming in nonchlorinated pools. Clinics distinguished skin and soft tissue lesions (typically sporotrichoid or subacute hand nodules) and lesions disseminated to joint and bone, often related with the local use of corticosteroids. In clinical microbiology, microscopy and culture are often negative because growth requires low temperature (30°C) and several weeks to succeed in primary cultivation. The treatment is not standardized, and no randomized control trials have been done. Therapy is a combination of surgery and antimicrobial agents such as cyclines and rifampin, with successful outcome in most of the skin diseases but less frequently in deep tissue infections. Prevention can be useful with hand protection recommendations for professionals and all persons manipulating fishes or fish tank water and use of alcohol disinfection after contact.

[Osteo-cutaneous Mycobacterium marinum infection of the elbow and reconstruction with radial collateral artery perforator-based propeller flap]

Mycobacterium marinum is an atypical and non-tuberculosis mycobacterium that mainly leads to cutaneous infections. Infections occur through inoculation of the organism through injury to the skin in the presence of contaminated water or fish. The patient often presents with unspecific symptoms and the evolution, in the absence of adequate treatment, is characterized by an expansion of the cutaneous lesion and a spread to deep structures. Infections of tendon sheaths and joints are described, rarely osteomyelitis. Sure diagnosis is hard to obtain and is established from the medical history and microbiological examination. There are no specific therapeutic guidelines. Double or triple antibiotherapy is often effective and should be continued several months after complete resolution of clinical signs. Surgical debridement is required in cases of invasive or resistant infections. We report the case of a young immunocompetent fishmonger with a rare osteocutaneous M. marinum infection of the elbow. Treatment included large surgical excision of infected skin and bone areas and a triple antibiotics administration. Reconstruction have been ensured by a radial collateral artery perforator-based propeller flap, satisfying appropriates functional and cosmetical concerns of this anatomical region. Surgery and appropriate antibiotics treatment were effective and allowed healing of an invasive cutaneous and bone M. marinum infection.

Inherited and acquired immunodeficiencies underlying tuberculosis in childhood

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb) and a few related mycobacteria, is a devastating disease, killing more than a million individuals per year worldwide. However, its pathogenesis remains largely elusive, as only a small proportion of infected individuals develop clinical disease either during primary infection or during reactivation from latency or secondary infection. Subacute, hematogenous, and extrapulmonary disease tends to be more frequent in infants, children, and teenagers than in adults. Life-threatening primary TB of childhood can result from known acquired or inherited immunodeficiencies, although the vast majority of cases remain unexplained. We review here the conditions conferring a predisposition to childhood clinical diseases caused by mycobacteria, including not only M.tb but also weakly virulent mycobacteria, such as BCG vaccines and environmental mycobacteria. Infections with weakly virulent mycobacteria are much rarer than TB, but the inherited and acquired immunodeficiencies underlying these infections are much better known. Their study has also provided genetic and immunological insights into childhood TB, as illustrated by the discovery of single-gene inborn errors of IFN-γ immunity underlying severe cases of TB. Novel findings are expected from ongoing and future human genetic studies of childhood TB in countries that combine a high proportion of consanguineous marriages, a high incidence of TB, and an excellent clinical care, such as Iran, Morocco, and Turkey.

Pediatric Cutaneous Nontuberculous Mycobacterium Infections in Singapore

BACKGROUND

Nontuberculous mycobacterium (NTM) infections are rare in children, with limited published studies. The course of the disease can be variable and there are no accepted treatment guidelines for the management of NTM infections in children.

OBJECTIVE

To review a cohort of pediatric patients admitted to a tertiary pediatric hospital in Singapore for cutaneous NTM infections.

METHODS

A retrospective review was performed of all children admitted to KK Women's and Children's Hospital with cutaneous NTM infections from 2002 to 2012.

RESULTS

Sixty-seven patients with positive NTM cultures from various body sites were identified. Eight of the 67 patients (11.9%) presented with cutaneous NTM without evidence of systemic involvement. The mean age at diagnosis for these eight patients was 10 years (range 5-21 yrs). Mycobacterium abscessus was the most common NTM isolated (five patients), followed by Mycobacterium hemophilium (two patients) and Mycobacterium kansasii (one patient). Most patients presented with isolated skin abscesses. Two patients were immunocompromised. Six patients required multidrug antibiotic treatment for a median duration of 5.5 months (range 3-17 mos). The median follow-up duration was 8.5 months (range 2 wks-29 mos).

CONCLUSION

Although the incidence of cutaneous NTM is rare, the diagnosis should be considered in patients presenting with chronic wounds. Most patients require treatment with multidrug antibiotic therapy, although uncomplicated abscesses can be treated with surgical incision and drainage alone.

Mycobacterium marinum SecA2 promotes stable granulomas and induces tumor necrosis factor alpha in vivo

SecA2 is an ATPase present in some pathogenic Gram-positive bacteria, is required for translocation of a limited set of proteins across the cytosolic membrane, and plays an important role in virulence in several bacteria, including mycobacteria that cause diseases such as tuberculosis and leprosy. However, the mechanisms by which SecA2 affects virulence are incompletely understood. To investigate whether SecA2 modulates host immune responses in vivo, we studied Mycobacterium marinum infection in two different hosts: an established zebrafish model and a recently described mouse model. Here we show that M. marinum ΔsecA2 was attenuated for virulence in both host species and SecA2 was needed for normal granuloma numbers and for optimal tumor necrosis factor alpha response in both zebrafish and mice. M. marinum ΔsecA2 was more sensitive to SDS and had unique protrusions from its cell envelope when examined by cryo-electron tomography, suggesting that SecA2 is important for bacterial cell wall integrity. These results provide evidence that SecA2 induces granulomas and is required for bacterial modulation of the host response because it affects the mycobacterial cell envelope.

Bacillus Calmette-Guérin (BCG) complications associated with primary immunodeficiency diseases

Primary immunodeficiency diseases (PIDs) are a group of inherited disorders, characterized by defects of the immune system predisposing individuals to variety of manifestations, including recurrent infections and unusual vaccine complications. There are a number of PIDs prone to Bacillus Calmette-Guérin (BCG) complications. This review presents an update on our understanding about the BCGosis-susceptible PIDs, including severe combined immunodeficiency, chronic granulomatous disease, and Mendelian susceptibility to mycobacterial diseases.

[Infections due to rapidly growing mycobacteria]

Rapidly growing mycobacteria (RGM) are ubiquitous in nature and widely distributed in water, soil and animals. During the past three decades we have observed a notable increment of infections caused by RGM, both localized and disseminated, as well as nosocomial outbreaks of contaminated medical equipment. The microbiological diagnosis of RGM infections includes direct microscopic observation and culture. The taxonomic identification is performed by phenotypic, biochemical, chromatographic and molecular biology techniques. The treatment differs from that of other mycobacteriosis like tuberculosis, owing to the variable in vitro susceptibility of the species of this group. The RGM are resistant to conventional antituberculous drugs, but can be susceptible to broad spectrum antimicrobial agents. In this study we comment on the significant aspects of human infections by RGM, including their biology, epidemiology, pathology, microbiological diagnosis, taxonomic identification, antimicrobial susceptibility and treatment.

TREATING DEEP-SEATEDMYCOBACTERIUM MARINUMINFECTION IN THE HAND: A REPORT OF THREE CASES

We report three cases of an unusual aggressive type of Mycobacterium marinum infection of the hand which had been a nightmare both for us and the patient. These were the patients in which even after repeated thorough surgical debridement and appropriate (drug sensitive) medical treatment over a period had resulted in amputation or devastation of the soft tissues so extensively that almost only the neurovascular bundle, bone and the skin were the only structures left (cosmetic fingers — no function) at the last debridement after which the infection has not recurred. By presenting this article we want to stress on certain points pertaining to diagnosis, management, varied presentation and of course the dreadful complications of deep-seated M. marinum infection.

Zoonotic bacteria, antimicrobial use and antimicrobial resistance in ornamental fish: a systematic review of the existing research and survey of aquaculture-allied professionals

Using systematic review methodology, global research reporting the frequency of zoonotic bacterial pathogens, antimicrobial use (AMU) and antimicrobial resistance (AMR) in ornamental fish, and human illness due to exposure to ornamental fish, was examined. A survey was performed to elicit opinions of aquaculture-allied personnel on the frequency of AMU and AMR in ornamental fish. The most commonly reported sporadic human infections were associated withMycobacterium marinum, whileSalmonellaParatyphi B var. Java was implicated in all reported outbreaks.Aeromonasspp. were most frequently investigated (n=10 studies) in 25 studies surveying ornamental fish from various sources. High levels of resistance were reported to amoxicillin, penicillin, tetracycline and oxytetracycline, which was also in agreement with the survey respondents' views. Studies on AMU were not found in our review. Survey respondents reported frequent use of quinolones, followed by tetracyclines, nitrofurans, and aminoglycosides. Recommendations for future surveillance and public education efforts are presented.

Disseminated Mycobacterium marinum infection in a hematopoietic stem cell transplant recipient

Mycobacterium marinum is a photochromogenic mycobacterium that is ubiquitous in the aquatic environment. In the general population, exposure to aquaria is the most common cause of M. marinum infection. Known as "swimmer's granuloma" or "fish tank granuloma," M. marinum is an occupational hazard for aquarium cleaners and fishermen. There are several reports in the literature of M. marinum infection in immunocompromised hosts, including those with solid organ transplants, but none in patients who have received stem cell transplants (SCTs). To our knowledge, this is a first report of disseminated M. marinum infection in an SCT recipient who continued to develop new skin lesions even after months of targeted therapy. The implications are that elderly patients who receive T-cell-depleted SCTs may be at prolonged risk for pathogens dependent on cellular immunity, and the presentation of illness with such pathogens may be more severe and widely disseminated than might otherwise be expected.

[Infections due to Mycobacterium marinum: a review]

Mycobacterium marinum belongs to the non-tuberculous or "atypical" mycobacteria. The reservoirs for these ubiquitous and slowly growing bacteria are both fresh water and salt water. In particular, aquaria should be considered as important source of hobby-related infections especially of fingers, hands and forearms. Affected are both immunosuppressed patients and persons with an intact immune system. Distinctive are erythematous plaques and nodules with tendency for hyperkeratosis, crusting, and superficial ulcerations, sometimes as sporotrichoid lymphocutaneous infection. The histology shows non-caseation granulomas containing epithelioid cells and Langhans giant cells. Using the Ziehl Neelsen staining, typical acid-fast rods are not always detectable. The molecular biological detection of mycobacterial DNA using polymerase chain reaction represents the standard method of diagnosis. Cryotherapy is frequently used as first treatment. For the often long-term tuberculostatic therapy, rifampicin, ethambutol, and clarithromycin are the most used agents.

Mycobacterium marinum infection of the deep structures of the hand and wrist: 25 years of experience

Mycobacterium marinum infection could have various presentations, from superficial skin infection to deep structure destruction. The prognosis is relatively poor when deep structure is involved as it is more destructive. The prognosis is even worse when operation is required. In the retrospective study of 136 patients who suffered this disease with deep structure involvement, their clinical presentations could be classified into benign and aggressive type. It was found that both types of presentation could be treated conservatively by medication alone. Benign presentations could be treated successfully with chemotherapy alone without complications. Patients with aggressive presentation were usually associated with worse prognosis as there were more complications regardless of the management option. Therefore, the clinical presentation not only had prognostic value but could also guide the treatment plan.

Highly variable clinical phenotypes of hypomorphic RAG1 mutations

Hypomorphic mutations that lead to "leaky" severe combined immunodeficiency presentation with partial protein function are increasingly being identified. Mutations in recombination-activating genes (RAGs) 1 and 2 cause immunodeficiency and dysregulation ranging from severe combined immunodeficiency to Omenn syndrome to more mild immunodeficiencies. We report here the cases of 3 patients with hypomorphic RAG1 mutations with distinct presentations. One patient had granulomatous skin disease and disseminated nontuberculous mycobacteria; the second patient presented with predominantly autoimmune manifestations; and the third patient presented with relatively late onset of infections and had isolated T-cell lymphopenia. These disparate and atypical presentations of hypomorphic RAG1 mutations highlight the role of RAG1 in immune function and autoimmunity and expand the disease spectrum linked to these genes.

Sanitary conditions of public swimming pools in Amman, Jordan

This study was carried out in the summer of 2005 and investigated all of active public swimming pools (85 out of 93) in Amman, the capital of Jordan. The aim of this study was to find out if these swimming pools are in compliance with Jordanian Standards for Swimming Pools Water (JS 1562/2004). The pools were surveyed against the water microbial quality and other physicochemical parameters indicated in the standards. Two samples from each pool were collected for microbial analysis and pools monitoring were carried out during the afternoon of the weekends when the pools are most heavily used. The results indicated overall poor compliance with the standards. Compliance of the pools water to the microbial parameters was 56.5%, for residual chlorine 49.4%, for pH 87.7%, water temperature 48.8%, and bathing load 70.6%. The results also indicated that water microbial quality deteriorated with time. Multivariate analysis showed significant association of water contamination with time of sample collection, residual chlorine, water temperature and load of swimmers. The poor compliance was attributed to lack of proper disinfection, staff training, proper maintenance, and timely inspection.

A review of mycobacteriosis in marine fish

Mycobacteriosis is a serious and often lethal disease of fish, affecting a wide range of species globally both in culture and wild settings. Caused by several species of the genus Mycobacterium, the disease has received considerable attention in recent years because of the discovery of new species in piscine hosts, epizootics in wild fisheries, and the ability of a few species to infect humans. The impact of this disease in aquaculture and the aquaria trade has been well reported and there is currently no widely accepted cure other than depopulation and facility disinfection. However, the impact on wild fisheries is poorly understood and may relate to species-specific interactions (host-pathogen) and possibly environmental stressors. In this review, much of what is known about mycobacteriosis in marine fish is summarized with particular attention to an epizootic in striped bass, Morone saxatilis, (Walbaum), in Chesapeake Bay, USA.

Occurrence of Mycobacterium spp. in ornamental fish in Italy

The occurrence of Mycobacterium spp. in freshwater and marine ornamental fish was studied in Italy from June 2002 to May 2005. Two surveys were carried out, one of aquarium fish sent to the Laboratory for diagnosis, and the other of prevalence of infection by mycobacteria in ornamental fish imported into Italy. Bacterial isolation was carried out from the spleen, kidney and liver, and the isolates were subsequently identified by biochemical tests. In the first survey, 387 fish were examined and Mycobacterium spp. were isolated from 181 (46.8%) fish. In the second survey 127 batches of ornamental fish from different countries were examined. Mycobacterium spp. were isolated from 38 (29.9%) batches. The following species were found: M. fortuitum, M. peregrinum, M. chelonae, M. abscessus, M. marinum, M. gordonae, M. nonchromogenicum and M. interjectum. There was a high prevalence of infection independent of the presence of macroscopic lesions. Mycobacterium fortuitum and M. chelonae were more prevalent than M. marinum in the samples examined.

Mycobacterium marinum osteomyelitis of a long bone

Mycobacterium marinum can uncommonly cause osteomyelitis of small bones of extremities. The reported cases in literature are reviewed. We report a rare case of long bone osteomyelitis which as far as we are aware, has never been described before. Even though this organism normally causes infection in the superficial cooler regions of the body, clinicians should be aware of the possibility of long bone osteomyelitis in patients with a history of immune compromise and the appropriate treatment strategy in such cases.

Sanitary conditions of public swimming pools in Amman, Jordan

This study was carried out in the summer of 2005 and investigated all of active public swimming pools (85 out of 93) in Amman, the capital of Jordan. The aim of this study was to find out if these swimming pools are in compliance with Jordanian Standards for Swimming Pools Water (JS 1562/2004). The pools were surveyed against the water microbial quality and other physicochemical parameters indicated in the standards. Two samples from each pool were collected for microbial analysis and pools monitoring were carried out during the afternoon of the weekends when the pools are most heavily used. The results indicated overall poor compliance with the standards. Compliance of the pools water to the microbial parameters was 56.5%, for residual chlorine 49.4%, for pH 87.7%, water temperature 48.8%, and bathing load 70.6%. The results also indicated that water microbial quality deteriorated with time. Multivariate analysis showed significant association of water contamination with time of sample collection, residual chlorine, water temperature and load of swimmers. The poor compliance was attributed to lack of proper disinfection, staff training, proper maintenance, and timely inspection.

Transmission of Mycobacterium marinum from fish to a very young child

Mycobacterium marinum causes tuberculosis in fish and can cause skin infections in humans who swim in contaminated water or who have direct contact with infected fish. We report the case study of an 18-month-old girl with M. marinum abscesses, who acquired the infection through indirect contact with a contaminated bucket. Appropriate cleaning of aquarium equipment is very important, especially with young children in the household.

Treatment of Mycobacterium marinum cutaneous infections

Mycobacterium marinum is a non-tuberculous mycobacterium found in non-chlorinated water, with worldwide prevalence. It is the most common atypical Mycobacterium that causes opportunistic infection in humans. It presents as a solitary, red-to-violaceous plaque or nodule with an overlying crust or verrucous surface, or as inflammatory nodules or abscesses, usually in a sporotrichotic type of distribution. Deep infections may also occur. Although diagnosis is confirmed by isolation and identification of the organism in practice diagnosis remains largely presumptive based on clinicohistological features and the response to treatment. Polymerase chain reaction allows the routine early detection of the organism from a biopsy specimen. In the near future, it seems possible that histopathological examination might be greatly assisted by the rapidly improving possibilities with in vivo imaging. There have been many therapeutic modalities used effectively in the treatment of M. marinum infections. Spontaneous remission has also been reported in untreated infections and in immunocompetent hosts. However, there is no proven treatment of choice because M. marinum is naturally multi-drug resistant species and treatment is based primarily on the personal experience and preference of individual investigators, without the benefit of large studies. In superficial cutaneous infections minocycline, clarithromycin, doxycycline and trimethoprim-sulfamethoxazole as monotherapy are effective treatment options, but drug resistance varies and thereby combination therapy usually of two drugs may be required. Ciprofloxacin has shown considerable effectiveness. In cases of severe infections, including those with a sporotrichoid distribution pattern, a combination of rifampicin and ethambutol seems to be the recommended regimen. The use of isoniazid, streptomycin and pyrazinamide as empirical treatment options should be avoided. Surgical treatment is not usually recommended and must be cautiously applied. Cryotherapy, X-ray therapy, electrodesiccation, photodynamic therapy and local hyperthermic therapy have been reported as effective therapeutic alternatives. M. marinum infection should always be included in the differential diagnosis of all cases with poor-healing wounds in upper extremities and a history of exposure to aquariums.

Differential green fluorescent protein expression from mycobacterial promoter constructs in Escherichia coli and Mycobacterium marinum

The Mycobacterium marinum G13 promoter is a sigma 70-like promoter that is more active by green fluorescent protein (gfp) differential fluorescence induction (DFI) assays when M. marium resides in an intracellular compartment as compared with growth in media. In assays using DFI, we found that the mycobacterial G13 promoter was also more active in a background of lower nutrient availability during logarithmic growth. This promoter, contained in an insert cloned upstream of a gfp reporter gene, is also active in Escherichia coli. When gfp expression assays of different plasmid constructs were performed in parallel with E. coli and M. marinum, expression in E. coli was maintained after deletion of both upstream and/or downstream regions proximal to the core promoter sequence. In M. marinum, however, although upstream deletions had no appreciable effect on gfp expression, promoter constructs with deleted downstream regions expressed 20- to 40-fold less gfp over all growth phases. The high-level expression of gfp was restored, however, in a clone containing approximately 100 bp downstream of the transcriptional start point. We have therefore utilized this gfp reporter assay of promoter activity to distinguish possible differences in requirements for gfp expression between different genera that utilize sigma 70-like promoter elements. We found that high levels of expression of gfp from the G13 promoter in M. marinum require downstream regions not necessary for gfp expression in E. coli.

Identification of mycobacteria by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry

Classical methods for identification of Mycobacterium species rely on morphology and biochemical profiles. Speciation of a Mycobacterium isolate using these standard methods is a lengthy process based on subjective data interpretation. In this study, Mycobacterium species were characterized by utilizing matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). This technology is designed to provide a characteristic mass spectral fingerprint based on desorbed ions from the cell surface. Thirty-seven strains were analyzed; these represented thirteen species and five subspecies that included the Mycobacterium tuberculosis complex and the M. avium-M. intracellulare complex, as well as rapid- and slow-growing mycobacteria. All 37 strains were analyzed in triplicate, and a database was generated. This method produced species-specific patterns for all but 1 of the 37 isolates and provided reliable differentiation at the strain level. The data suggest that whole-cell MALDI-TOF MS has potential as a rapid and reproducible method for the identification and characterization of Mycobacterium species.

In vivoandin vitrogrowth ofMycobacterium marinumat homoeothermic temperatures

Mycobacterium marinum can cause systemic infection in fishes and skin infection in humans. Most strains grow better at <37 degrees C, which can explain the rarity of infections in humans. The ability of strains from humans and fish to grow in various conditions, and in macrophages from carp, humans, and mouse was evaluated, as was the ability of the three fish isolates to infect mice. Significant differences of growth in vitro and in vivo were observed. All fish strains caused both footpad and deep tissue infections, and two, which grew very poorly or not all at 37 degrees C, proliferated in mammalian macrophages.

Host genetic factors and mycobacterial infections: lessons from single gene disorders affecting innate and adaptive immunity

This review summarizes the association of increased susceptibility to mycobacterial disease in patients with genetic defects affecting innate and adaptive immunity. The optimum function of CD4 T-cell and macrophage function is critically important for immunity against mycobacteria. Antibody, complement and neutrophil function is not required for effective anti-mycobacterial immunity.

Congenital immunodeficiencies and sepsis

OBJECTIVE

Because a hallmark of congenital immunodeficiency disorders is susceptibility to recurrent, unusual and/or severe infections, an effort was undertaken to identify a subset of these patients with an increased risk for sepsis.

DESIGN

Literature review.

RESULTS

Twenty congenital immunodeficiency disorders were identified with increased sepsis susceptibility.

CONCLUSION

Distinguishing patients with congenital immunodeficiencies from others with sepsis has important implications for the future well-being of the immunodeficient patient because many of the diseases are modified favorably by appropriate treatment. In addition, better understanding of sepsis in the setting of congenital immunodeficiency has numerous implications for both immunodeficiency and sepsis research. As a group, these disorders define components of the human immune system that are essential for defense against severe infection and demonstrate immunologic themes underlying sepsis susceptibility.

Mycobacterium marinum: the generalization and specialization of a pathogenic mycobacterium

Mycobacterium marinum is being used increasingly as a model for understanding pathogenic mycobacteria. However, recently discovered differences between M. marinum and M. tuberculosis suggest that adaptation to specialized niches is reflected in unique strategies of pathogenesis. This review emphasizes the areas in which studying M. marinum has made contributions to the understanding of tuberculosis, as well as the potential for using characteristics unique to M. marinum for understanding general issues of host-pathogen interactions.

Fish tank exposure and cutaneous infections due to Mycobacterium marinum: tuberculin skin testing, treatment, and prevention

In the present study, 8 patients with soft tissue infection due to Mycobacterium marinum are described, and contemporary data on treatment are reviewed. Six patients had positive cultures, all patients had cutaneous exposure to fish tanks, 7 had sporotrichoid lesions, and 2 had deep infection. All 7 tested patients had tuberculin skin test reactions > or =10 mm. Six patients with disease limited to the skin were successfully treated with 2-drug combination therapy, including clarithromycin, ethambutol, and rifampin. Optimal treatment should include 2 drugs for 1-2 months after resolution of lesions, typically 3-4 months in total. Deeper infections may require more prolonged treatment and surgical debridement. Positive tuberculin reactions may be due to infection with M. marinum. Persons with open skin lesions or immunosuppression should avoid cutaneous contact with fish tanks.

Molecular diagnosis of nontuberculous mycobacteria

PURPOSE OF REVIEW

Diagnosis of infection due to nontuberculous mycobacteria is not easy, as it must be distinguished from colonization or contamination by other nontuberculous mycobacteria. Molecular methods offer many advantages over conventional methods of identification. The results are obtained rapidly, are reliable and reproducible, and even mixed or contaminated cultures can be examined. This review highlights the recent advances in molecular techniques for identification of nontuberculous mycobacteria.

RECENT FINDINGS

Nontuberculous mycobacteria are ubiquitous towards the environment and have the potential to colonize and cause serious infection. An increasing number of species and clinical presentations are being described, and progress has been made towards the understanding of the underlying predisposing factors. Disease caused by nontuberculous mycobacteria is often associated with various forms of immunosuppression, particularly HIV infection, whereas mild forms of immune defects have been observed in some patients who, apart from their nontuberculous mycobacterial disease, seem to be healthy on initial examination. Molecular techniques have shown their usefulness for the identification of most mycobacteria. Probes are widely used in clinical laboratories for the identification of the most common mycobacterial species. Because automated DNA sequencing and the programs for analysing sequence data have become technically simpler, polymerase chain reaction-based sequencing is now used in many mycobacterial reference laboratories as a routine method for species identification.

SUMMARY

Significant advances have been made with molecular tools for diagnosis of mycobacteria. The DNA microarray technique holds great promise for the future because it is easy to perform, it can be readily automated, and it allows the identification of a large number of mycobacterial species in one reaction.